Method and apparatus for electrochemically machining airfoil blades

ABSTRACT

In accordance with a preferred, exemplary embodiment of the invention, a method of forming a blisk from a workpiece is disclosed. The workpiece (12) includes a blank (14) having oppositely facing first and second faces defined by a radially inner base, a radially outer top, a first edge, and a second edge. The method comprises the steps of: positioning first and second electrodes (18,20) adjacent to the first and second faces, respectively, of the blank; supplying (48) a positive voltage to the blank and a negative voltage to the first and second electrodes; channelling an electrolyte (28) between the blank and the first and second electrodes for electrochemically machining the blank; moving the first and second electrodes toward (U,X) the first and second faces of the blank; and moving the workpiece toward (Z) the first and second electrodes. An apparatus is disclosed for practicing the method and the invention can be used for electrochemically machining an airfoil.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to concurrently filed application Ser. No.049,079 entitled "Electrodes for Electrochemically Machining AirfoilBlades" by N. A. Bruns et al, which is assigned to the same assignee asthe present application.

BACKGROUND OF THE INVENTION

This invention relates generally to electrochemically machining ofmetallic parts, and, more specifically, to electrochemically machiningairfoils.

Electrochemical machining (hereinbelow also referred to alternatively assimply machining) is a conventional process in which a workpiece istypically provided with a positive voltage to create an anode, and anelectrode is provided with a negative voltage to create a cathode. DCvoltages between about 5-25 volts and up to about 15-30,000 amps aretypically used. An electrolyte is then channeled in the space or gapbetween the workpiece and the electrode for electrochemically machiningthe workpiece. Such gap must be accurately maintained to avoid damagingsparking, or arcing, which would occur with gaps which are too small orcause too little electrolyte flow.

The prior art includes various methods for electrochemically machiningairfoil blades, either singly or on a unitary integral bl(aded-d)iskassembly, i.e. blisk. Leading and trailing edges of an airfoil blade areespecially difficult to machine precisely, and the prior art teachesvarious apparatus therefor.

Blisks having high camber, high twist and/or high solidity createsubstantial problems for economically electrochemically machining bladesthereon. Camber refers to the angle of blade tip with respect to acenterline axis. Twist refers to the difference in camber angles betweenblade root and blade tip. And solidity refers to the number of bladeswith respect to the circumference of a blisk with high solidityindicating relatively closely-spaced blades.

An apparatus for efficiently and economically electrochemicallymachining blisks, therefore, must do so in relatively few operations andwithout utilizing relatively complex structures.

OBJECTS OF THE INVENTION

Accordingly, an object of the present invention is to provide a new andimproved method and apparatus for electrochemically machining anairfoil.

Another object of the present invention is to provide a new and improvedmethod and apparatus for electrochemically machining a blisk.

Another object of the present invention is to provide a new and improvedmethod and apparatus for electrochemically machining an airfoil in asingle operation from a workpiece blank.

Another object of the present invention is to provide a new and improvedmethod and apparatus for precisely electrochemically machining bothleading and trailing edges of a workpiece blank in addition to thesurfaces therebetween.

Another object of the present invention is to provide a new and improvedmethod and apparatus for electrochemically machining a platform betweenadjacent blades on a blisk simultaneously with electrochemicallymachining a blade thereon.

SUMMARY OF THE INVENTION

In accordance with a preferred, exemplary embodiment of the invention, amethod of forming a blisk from a workpiece is disclosed. The workpieceincludes a blank having oppositely facing first and second faces definedby a radially inner base, a radially outer top, a first edge, and asecond edge. The method comprises the steps of:

positioning first and second electrodes adjacent to the first and secondfaces, respectively, of the blank;

supplying a positive voltage to the blank and a negative voltage to thefirst and second electrodes;

channeling an electrolyte between the blank and the first and secondelectrodes for electrochemically machining the blank;

moving the first and second electrodes toward the first and second facesof the blank; and

moving the workpiece toward the first and second electrodes.

In accordance with another embodiment of the invention, an apparatus isdisclosed for practicing the method.

In accordance with another embodiment of the invention, a new andimproved electrode pair is disclosed for electrochemically machining anairfoil.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are setforth in the appended claims. The invention, in accordance withpreferred and exemplary embodiments thereof, and including additionalobjects and advantages, is more particularly described in the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 is a perspective view of an apparatus, in part schematic,including a machine for electrochemical machining in accordance with apreferred embodiment of the present invention.

FIG. 2 is a plan view of a portion of the electrochemical machineillustrated in FIG. 1 in a horizontal plane.

FIG. 3 is a plan view of a portion of the electrochemical machineillustrated in FIG. 1 in a vertical plane disposed normal to thehorizontal plane of FIG. 2.

FIG. 4 is a plan view of a portion of the electrochemical machineillustrated in FIG. 1 in a second vertical plane normal to both thehorizontal plane of FIG. 2 and the vertical plane of FIG. 3.

FIG. 5 is a perspective view of a portion of a rough workpiece used formanufacturing a blisk.

FIG. 6 is a perspective view of a roughing electrode usable forelectrochemically machining blanks from the rough workpiece illustratedin FIG. 5.

FIG. 7 is a sectional view of a portion of the roughing electrode ofFIG. 6 and a portion of the rough workpiece illustrated in FIG. 5illustrating electrochemical machining thereof.

FIG. 8 is a perspective, partly sectional, view of a portion of a bliskworkpiece formed from the rough workpiece illustrated in FIG. 5.

FIG. 9 is an elevation view of a portion of a finally electrochemicallymachined blisk formed from the workpiece illustrated in FIG. 8.

FIG. 10 illustrates front perspective views of complementary electrodesusable for electrochemically machining blisk blades in accordance withone embodiment of the invention.

FIG. 11 illustrates back perspective views of the electrodes illustratedin FIG. 10.

FIG. 12 is a top plan view of the electrodes illustrated in FIGS. 10 and11 in a machining position over the workpiece of FIG. 8.

FIG. 13 is a side view of the electrode pair illustrated in FIG. 12taken along line 13--13.

FIG. 14 is a sectional view in part through the electrode pairillustrated in FIG. 17 taken along line 14--14.

FIG. 15 is a perspective view of the workpiece 12 positioned just priorto the entry of a workpiece blank between the electrode pair illustratedin FIG. 12.

FIG. 16 is a perspective view of an electrolyte outlet block taken alongline 16--16 in FIG. 12.

FIG. 17 is a partly sectional view taken along a centerline of theflowpath of electrolyte through the electrode pair illustrated in FIG.12 taken along line 17--17.

FIG. 18 is a sectional view of a portion of one electrode and theworkpiece blank illustrated in FIG. 14 taken along line 18--18.

DETAILED DESCRIPTION

Illustrated in FIG. 1 is an apparatus 10 for electrochemically machiningor forming a blisk from a workpiece 12 having a plurality ofcircumferentially-spaced workpiece blanks 14. The apparatus 10 includesan electrochemical machine 15 having a housing 16, a pair of electrodesincluding a first electrode 18 and a second electrode 20, and means 22for mounting the electrode pair to the housing 16. Means 24 for mountingthe workpiece 12 to the housing 16 are also provided.

The apparatus 10 further includes means 26 for channeling electrolyte 28to the electrode pair and means 30 for powering the electrode pair witha negative voltage and the workpiece 12 with a positive voltage. Theelectrolyte 28 is conventional and may include a solution of water andsodium chloride and/or sodium nitrate, or other effective electrolytesolution.

The electrolyte channeling means 26 includes a conventional electrolytesupply 32, which provides relatively clean and temperature controlledelectrolyte 28 to the electrode pair 18, 20 through a supply conduit 34.The supply 32 is conventional and includes, in part, a high pressurepump, in-line filter, temperature controlling means and suitable controlvalves (all not shown). A return conduit 36 receives the electrolyte 28from the electrode pair for return to the supply 32. A drain 38 formedin the housing 16 is provided for capturing any electrolyte 28 whichleaks and returning it to the supply 32 through a drain conduit 40connected to the return conduit 36. A conventional pump 42 is disposedin the return conduit 36 for returning electrolyte 28 from the electrodepair and the drain 38 to the supply 32.

The power means 30 includes a conventional power supply 44 effective forproviding DC power between 5 and 25 volts and at up to 15,000 amperes.Current up to 30,000 amperes could also be used for machining relativelylarge workpieces 12. A positive cable 46 connects the power supply 44 tothe workpiece 12. A negative cable 48 connects the power supply 44 toboth the first and second electrodes 18 and 20. A negative voltage issupplied through the cable 48 to the first and second electrodes 18 and20, and a positive voltage is supplied through the cable 46 to theworkpiece 12.

The apparatus 10 further includes a conventional control means 50suitably connected to and effective for electrically controlling theelectrode mounting means 22, the workpiece mounting means 24, the powermeans 30 and the channeling means 26.

The electrode mounting means 22 provides colinear translation of theelectrode pair with translation of the first electrode 18 occurring in aU direction or axis, and translation of the second electrode 20occurring in an X direction or axis parallel to the U direction. Themeans 22 also mounts the electrode pair as described in moreparticularity below for rotation in an annular C direction. Aconventional elastic seal 52 allows the mounting means 22 to translateand rotate while preventing the electrolyte 28 from contacting theconventional mechanisms providing for movement in the X, U, and Cdirections. The seal 52 includes, for example, bellows-like folds (notshown) for accommodating X and U translation. And, at a radially outerperimeter thereof, the seal 52 includes an annular sliding seal foraccommodating C rotation.

The workpiece mounting means 24, also more particularly describedhereinbelow, is effective for translating the workpiece 12 in a Zdirection or axis and rotating the workpiece 12 in an annular Bdirection. A conventional elastic seal 54 is provided for allowing themounting means 24 to translate and rotate while preventing theelectrolyte 28 from contacting the conventional mechanisms of themounting means 24 in the housing 16. The seal 54 includes, for example,bellows-like folds (not shown) for accommodating Z translation. And, ata radially inner perimeter thereof, the seal 54 includes an annularsliding seal for accommodating B rotation.

FIGS. 2-4 illustrate in more particularity certain features of thehousing 16. The electrode mounting means 22 includes a first turntable56 suitably attached to the housing 16 and rotatable in the C directionabout a first centerline or rotation axis 58 extending normal thereto.The turntable 56 is conventionally mounted for allowing rotation ineither a positive or negative C direction about the first axis 58.

The mounting means 22 further includes a first translation means 60having a first L-shaped support 62 suitably connected to the firstturntable 56 for movably mounting the first electrode 18 thereto. Thefirst support 62 extends through the elastic seal 52 and is suitablyconnected to a conventional power screw (not shown), for example, whichis effective for causing the support 62 to translate along the U axis ineither a positive or negative direction.

The mounting means 22 also includes a second translation means 64effective for translating the second electrode 20 along the X axis. Thesecond translation means 64 includes a second L-shaped support 66suitably connected to the first turntable 56 for movably mounting thesecond electrode 20 thereto. The second support 66 extends through theelastic seal 52 and is suitably connected to a conventional power screw,for example, effective for translating the second support 66 along the Xaxis in either a positive or negative direction.

The first and second electrodes 18 and 20 are mounted on the first andsecond supports 62 and 66, respectively, along a longitudinalcenterline, or first translation, axis 68, which is parallel to the Xand U axes. The first translation axis 68 is perpendicular to the firstrotation axis 58.

The workpiece mounting means 24 includes a shaft 70 having a shoulderagainst which the workpiece 12 is suitably secured by a nut 72, forexample. The shaft 70 is suitably coaxially connected to a secondturntable 74. The turntable 74 is suitably connected to a thirdtranslation means 76 slidingly attached to the housing 16. Thetranslation means 76 includes a housing 78 which contains conventionalstructures for rotatably supporting the second turntable 74 thereto forobtaining rotation thereof in the B direction. The housing 78 isconventionally attached to the housing 16 by sliding rails 80, whichincludes a conventional feed screw (not shown), which allow fortranslation of the housing 78 along the Z axis in either positive ornegative directions.

The second turntable 74 and shaft 70 include a centerline or secondrotation axis 82, about which axis 82 the turntable 74 rotates in eitherpositive or negative B directions. The second rotation axis 82 iscoplanar with the first rotation axis 58 and perpendicular thereto.

The control means 50 is suitably connected to and is effective forindependently controlling the movement of the first and secondturntables 56, 74, and the first, second and third translation means 60,64, and 76. The control means 50 is effective for controlling rotationof the second turntable 74 to index a first blank 14 of the workpiece 12into a machining position and then translating the workpiece 12 towardthe electrode pair. The control means 50 is also effective forcontrolling rotation of the first turntable 56 and translation of thefirst and second electrodes 18 and 20 connected thereto. As will bedescribed in more particularity hereinbelow, the control means 50coordinates the independent movement of the electrode pair and the blank14 along the X, U, C and Z directions so that the electrodes 18 and 20are brought into an initial machining position adjacent to the blank 14.The control means then similarly coordinates the independent, butcoordinated, movement thereof during machining. Such movements mayinclude rotation of the electrode pair to twist the pair relative to theblank 14.

Illustrated in FIG. 5 is a perspective, partly sectional view of a roughworkpiece 84, from which the workpiece 12 is formed. The blanks 14 maybe formed in the workpiece 84 using conventional multiaxis millingmachines, or they may be formed using the machine 15.

Illustrated in FIG. 6, for example, is a roughing electrode 86 includinga nonconductive body 88 suitably attached to a supporting ring 90 at oneend thereof, and having a substantially flat plate electrode 92 at theother end thereof. The electrode 92 and body 88 include anairfoil-shaped aperture 94 therethrough.

The electrode 86 may be suitably connected to either or both of thesupports 62 and 66 of the first translation means 60. The roughworkpiece 84 is suitably connected to the shaft 70 of the mounting means24. The negative cable 48 is suitably connected to the plate electrode92, and the positive cable 46 is suitably connected to the workpiece 84.The workpiece 84 is then moved in the Z direction toward the electrode84, as illustrated in more particularity in FIG. 7. Electrolyte 28 ischanneled through the aperture 94, and electrochemical machining occursbetween plate electrode 92 and the workpiece 84 for machining the blank14. For twisted blanks 14, the first turntable 56 rotates the electrode86 in the C direction as the workpiece 84 is translated theretoward inthe Z direction until the blank 14 is completely machined.

The workpiece 84 and the electrode 86 are then retracted from each otherand then the workpiece 84 is indexed in the B direction by the secondturntable 74 for repeating the machining operation described above foran adjacent blank 14. This process is repeated until all blanks 14 areformed in the workpiece 84.

FIG. 8 illustrates a perspective view of a portion of the workpiece 12after having been electrochemically machined by the apparatus 10. Thedashed line outline 96 represents the initial outline of the workpiece12 including the blanks 14. The solid line outline 98 represents theshape of the finally-formed blisk 98. The difference between the solidand dashed lines is typically about 30 mils (i.e. 0.030 inch), forexample.

The blisk 98 includes a plurality of circumferentially spaced blades100, each having a first, generally concave side 102 and a second,generally convex side 104 defined by a leading edge 106, a trailing edge108, a tip 110, and a root 112. Between the roots 112 of adjacent blades100 is a platform 114. The blisk 98 further includes a first shoulder116 extending upstream from the platforms 114 and the leading edges 106,and a second shoulder 118 extending aft of the platforms 114 and thetrailing edges 108. The first and second shoulders 116 and 118 are shownschematically and may include conventional curvic coupling means (notshown) formed therein for securing the blisk 98 to adjacent structuresin a gas turbine engine.

Each of the workpiece blanks 14 includes a first face 120 and anopposite second face 122 defined between a first radially extending edge124, a second radially extending edge 126 disposed opposite to the firstedge 124, a radially outer top 128, and a radially inner base 130.Between the bases 130 of adjacent blanks 14 is a land 132.

The first face 120, second face 122, first edge 124, second edge 126,top 128, base 130, and land 132 of the workpiece 12 represent theinitial structures before electrochemical machining resulting in finalstructures of the blisk 12 including the first side 102, the second side104, trailing edge 108, leading edge 106, tip 110, root 112, andplatform 114, respectively.

Illustrated in FIG. 9 is a top view of the blisk 12 including blades100. The camber of the blade tip 110 is represented by the angle B froman axial centerline 134 of the blisk 12 to a chord 136 drawn between thetrailing edge 108 and the leading edge 106 of the blade tip 110. Thecamber of the root 112 is represented by the angle A from the centerline134 to a similarly defined chord 138 of the root 112. The twist angle ofthe blade 100 is represented by the angle C, the difference between thecamber angles A and B. One feature of the present invention is theability to electrochemically machine a blisk 12 having blades 100 withrelatively high camber and twist, for example, a camber angle A of about30°, a camber angle B of about 65°, with a twist angle C of 35°. Thesolidity of the blisk 12 is represented by the number of blades 100relative to the circumference; and the present invention is effectivefor forming blisks 12 having relatively high solidity, for example, ofabout 22 blades in a blisk 12 having an outer diameter of about 7.5inches and, for another example, about 32 blades in a blisk 12 having anouter diameter of about 6 inches.

Illustrated in FIGS. 10 and 11 are perspective isolated views of thefirst and second electrodes 18, 20 showing the fronts and backs thereof.The electrode pair may be made of any suitable electrically-conductingmaterial having adequate structural strength such as, for example, acopper-aluminum alloy.

The first electrode 18 includes a generally rectangular support portion140 having a plurality of apertures 142 through which retention bolts144 extend for securing the electrode 18 to the support 62 (see FIG.15). Electrode 18 further includes a working portion 146 for channelingelectrolyte 28 and electrochemically machining the first face 120 of theblank 14.

The second electrode 20 similarly includes a support portion 148 havinga plurality of the apertures 142 for receiving a plurality of the bolts144 to secure the electrode 20 to the support 66 (see FIG. 15). Thesecond electrode 20 also includes a working portion 150 for channelingthe electrolyte 28 and for electrochemically machining the second face122 of the blank 14.

The working portion 146 of the first electrode 18 includes in sequentialplacement an inlet end 152, a converging face 154, a first throat face156, a generally convex work face 158, a second throat face 160, adiverging face 162, and an outlet end 164. Similarly, the workingportion 150 of the second electrode 20 includes in sequential placementan inlet end 166, a converging face 168, a first throat face 170, agenerally concave work face 172, a second throat face 174, a divergingface 176, and an outlet end 178.

As illustrated in more particularity in FIGS. 12-14, the first andsecond electrodes 18, 20 are positionable about one of the blanks 14 sothat the working portions 146 and 150 define therebetween in sequentialplacement an inlet 180, a converging nozzle 182, a first throat 184, aworking space 186 for receiving the blank 14, a second throat 188, adiverging nozzle 190 and an outlet 192. More specifically, the workingportions 146 and 150 are spaced from and face each other so that theinlet ends 152, 166; converging faces 154, 168; first throat faces 156,170; work faces 158, 172; second throat faces 160, 174; diverging faces162, 176; and outlet ends 164, 178 define therebetween the above recitedelements 180-192, respectively.

As illustrated, for example, in FIGS. 12 and 15, the electrolytechanneling means 26 further includes a nonconductive inlet block 194suitably fixedly connected to the second electrode 20 by a pair of bolts196, for example, and a nonconductive outlet block 198 suitably fixedlyconnected to the first electrode 18 by another pair of the bolts 196,for example. The blocks 194, 198 are made from a suitable electricallynonconductive material which is also noncorrosive and will not absorbthe electrolyte 28, such as, for example, a laminated fiberglass/epoxymaterial conventionally known as Military Specification G-10. The blocks194, 196 are suitably connected in fluid communication with the conduits34, 36, respectively, by hollow bushings 200, 202, respectively, whichare threadingly engaged in the blocks 194, 198.

As illustrated in more particularity in FIGS. 16 and 17, the inlet block194 includes a generally diverging inlet plenum 204 in fluidcommunication with bushing 200, and the outlet block 198 includes agenerally converging outlet plenum 206 in fluid communication withbushing 202. FIGS. 12, 14 and 17 illustrate that the inlet plenum 204 isaligned in fluid communication with substantially the entire inlet 180of the electrode pair, and the outlet plenum 206 is aligned in fluidcommunication with substantially the entire outlet 192 of the electrodepair.

FIGS. 12, 14 and 17 illustrate the electrodes 18 and 20 in an operatingposition with a first workpiece blank 14 positioned between the workfaces 158 and 172. Inasmuch as the electrolyte 28 is channeled throughthe inlet block 194 between the working portions 146 and 150 and out theoutlet block 198, it is desirable to provide suitable means for sealingthe electrodes 18, 20 to substantially prevent leakage of theelectrolyte 28, which could cause undesirable electrochemical machiningof unintended portions of the blisk 12. The sealing means includes aninlet seal 208 defined by a seal portion 210 of the inlet block 194,which is slidingly engageable with the inlet end 152 of the firstelectrode 18. Inasmuch as the inlet block 194 is fixedly secured to thesecond electrode 20, an effective seal therebetween is also provided.The inlet seal 208 allows the first electrode 18 to move relative to theinlet block 194 and provide an effective seal which substantiallyprevents leakage of electrolyte 28 at the inlet 180.

The sealing means also includes a similar outlet seal 212 defined by aseal portion 214 of the outlet block 198, which is slidingly engageablewith the outlet end 178 of the second electrode 20. Inasmuch as theoutlet block 198 is fixedly secured to the first electrode 18, aneffective seal is formed therebetween. The outlet seal 212 provides aseal which is effective for accommodating the relative movement betweenthe outlet block 198 and the second electrode 20 for substantiallypreventing leakage of the electrolyte 28 at the outlet 192.

As illustrated in FIGS. 10, 13 and 17, the sealing means furtherincludes a top seal 216, which is positioned over the top 128 of theblank 14. The top seal 216 is defined by slidingly engageable sealportions of the working portions 146, 150 of the first and secondelectrodes 18, 20. More specifically, the top seal 216 includes, in anexemplary embodiment, a nonconductive seal block 218 fixedly connectedto one end of the working portion 150 of the electrode 20 by a pluralityof screws 220. The seal block 218 is also made of a suitablenonconductive material such as the G-10 described above. Top seal 216further includes a complementary recess 222 formed in the opposing endof the working portion 146 of the first electrode 18. The top seal 216accommodates relative movement between the electrodes 18 and 20 whileproviding sliding movement between the block 218 and the recess 222 toprovide a seal for substantially preventing the leakage of electrolyte28 therethrough.

The seal block 218 and recess 222 arrangement is particularly effectiveto minimize any radial deflection of the primarily transverse flow ofthe electrolyte 28 as best seen in FIG. 17. Any such radial deflectioncould cause machining of undesirable radii at the intersections of theblank top 128 and the first and second edges 124, 126 in some blank 14designs.

In other designs the relatively complex block 218/recess 222 arrangementmay be eliminated, and a simpler seal 216 may be used instead. Forexample, a simple tongue and groove seal may be located in the area inwhich the block 218 is shown. Suitable U-shaped recesses could be formedin the electrode pair to face each other, and an elongate flat membercould be positioned in the recesses to create the tongue and groove sealwhen the electrodes 18 and 20 are positioned together (not shown).

As illustrated in FIGS. 10-13, the sealing means further includes afirst bottom seal 224 and a similar second bottom seal 226 spaced fromand positioned opposite to the top seal 216 for substantially preventingthe leakage of electrolyte 28 from at least portions of the convergingnozzle 182 and the diverging nozzle 190 radially towards the first andsecond shoulders 116, 118 of the workpiece 12 (see FIG. 17). In theexemplary embodiment illustrated, the bottom seals are also positionedto prevent similar radial leakage from also the first and second throats184 and 188, although in other designs they need not be so positioned.

The first bottom seal 224 includes a nonconductive seal pad 228 suitablyfixedly connected to a support end 229 of the working portion 146 of thefirst electrode 18 by a pair of screws 230, for example. The pad 228 isformed of a suitable nonconductive material such as G-10, as abovementioned. The pad 228 extends from the working portion 146 and over theconverging face 154 and the first throat face 156 of the first electrode18. A complementary recess 232 is formed in the working portion 150 ofthe second electrode 20 over the first throat face 170 and theconverging face 168 for receiving the pad 228 in reciprocatingengagement therewith.

Similarly, the second bottom seal 226 includes a similar nonconductiveseal pad 234 (G-10 material) fixedly attached to a support end 235 ofthe working portion 150 of the second electrode 20 by a pair of similarscrews 230, for example. The seal pad 234 extends from the workingportion 150 over the diverging face 176 and the second throat face 174.A complementary recess 236 is formed in the working portion 146 of thefirst electrode 18 over the diverging face 162 and the second throatface 160 for receiving the pad 234 in reciprocating engagementtherewith.

When the electrodes 18 and 20 are positioned for machining as shown inFIG. 12, the seal pads 228, 234 overlap the recesses 232, 236,respectively, for creating seals which accommodate relativetranslational movement of electrodes 18 and 20 and substantiallypreventing leakage of electrolyte 28 in the radial direction between theworking space 186 and both the inlet 180 and the outlet 192 (see FIG.14). Of course, such overlapping members have relatively small gapstherebetween, but they are nevertheless effective for reducing andsubstantially preventing leakage which would otherwise occur withouttheir use.

FIG. 15 illustrates the relative position of the workpiece 12 andelectrodes 18 and 20 just prior to movement into final position forelectrochemical machining. In particular, the workpiece 12 is suitablysecured to the shaft 70 by the nut 72. Between the nut 72 and theworkpiece 12 is an electrically conducting spacer block 238 to which anend 240 of the positive cable 46 is suitably secured by a pair of bolts242, for example. The block 238 provides an electrical contact for flowof current to the workpiece 12. Of course, the workpiece 12 is suitablyconventionally electrically insulated from the remainder of the shaft70, for example by suitable insulating sleeves and spacers (not shown).

Alternatively, the cable 46 could be suitably connected to the shaft 70to provide current through the center of the shaft 70 to the workpiece12. In such an arrangement the cable 46 would be hidden entirely withinthe housing 16 and shaft 70, thus providing additional space in theworking area of the machine 15 where the workpiece 12 is located.

The negative cable 48 includes a first end 244 suitably fixedly securedto the first electrode 18 by a similar bolt 242, and a second end 246suitably fixedly secured to the second electrode 20 by another bolt 242,for example.

FIG. 17 illustrates the workpiece 12 including the first blank 14relative to the electrodes 18 and 20 at a point in time at finalelectrochemical machining of the blank 14. FIG. 14 illustrates a crosssection through the structure shown in FIG. 17 at about 50 percent ofthe radial height of the blank 14. Shown in solid line is a finallymachined blade 100 and the positions of the electrodes 18 and 20 and theblocks 194 and 198. Shown in dashed line is the outline of the workpieceblank 14, and the relative positions of the electrodes 18 and 20 and theblocks 194 and 198 just prior to commencement of electrochemicalmachining. A gap of about 8 mils for electrolyte flow between the blank14 and the machining portions of the electrodes 18, 20 is accuratelymaintainable using the apparatus of this invention.

The preferred embodiment of the invention includes several features forensuring that a precisely machined blade 100 of the blisk 98 resultsfrom a single operation of electrochemical machining of a blank 14 ofthe workpiece 12. In particular, and for example, the inlet plenum 204is shaped as shown in FIGS. 14 and 17 in a diverging nozzle to result ina rapid transition of flow from the bushing 200 to a substantiallyuniform flow at the inlet 180 of the electrode pair. The convergingnozzle 182 and the first throat 184 are provided in part to assist inensuring a uniform flow of the electrolyte 28 along the entire radialextent of the blank 14 from the base 130 to the top 128.

The first throat 184 additionally has a finite length L₁, which is notsimply a single plane, which is effective for preventing the formationof a vena contracta downstream of the throat 184 to additionally ensureuniform flow. Furthermore, throat 184 is positioned to extend at leastover a portion of the first edge 124 of the blank 14 in the initialcutting position prior to removal of material from the blank 14. Thiswill ensure that any burr 248 which might otherwise form at the firstedge 124 during machining will be removed by electrochemical machiningaction partly by the first throat faces 156 and 170. Such a burr 248 isundesirable because it might lead to damaging sparking.

The work faces 172 and 158 are suitably conventionally shaped forobtaining the desired shape of the first and second sides 102, 104,respectively, of the blade 100, and in the example illustrated willmachine generally convex and concave sides, respectively.

The second throat 188 similarly has a finite length L₂ to help ensure auniform flow of the electrolyte 28 along the entire radial extentthereof from the base 130 to the top 128 of the blank 14, and over thesecond edge 126. Both the lengths L₁ and L₂ should not be so large as toeffect undesirable pressure losses therefrom. The second throat 188 alsoextends at least over a portion of the second edge 126 of the blank 14in the initial cutting position to ensure that any burr 250 which mightform along the second edge 126 is removed during electrochemicalmachining to avoid undesirable sparking.

The blank 14 illustrated in FIG. 14 has an arcuate camber line 249extending from the first edge 124 to the second edge 126. The electrodepair is dimensioned in a preferred embodiment so that the camber line249 is positionable to extend partially into the first and secondthroats 184, 186 to remove burrs as above described. Also, the relativeposition of the camber line 249 with respect to the outlet end of thefirst throat 184 and the inlet end of the second throat 188 helpscontrol the final chord length and locations of the leading and trailingedges 106, 108 of the blade 100.

The first and second throats 184 and 188 also have widths W₁ and W₂,respectively, which define a first throat flow area A₁ of the entireradial extent of the first throat 184, and a second throat flow area A₂of the entire radial extent of the second throat 188. The first throatflow area A₁ and the width W₁ are preferably larger than the secondthroat flow area A₂ and the width W₂, respectively. This is preferred toprovide a predetermined flow restriction at the downstream side of theworking space 186 to partly ensure that uniform radial flow of theelectrolyte 28 is maintained across the entire radial extent of theblank 14. This also partly ensures uniform electrochemical machining andreduces the likelihood of any undesirable sparking which might otherwiseoccur in areas of nonuniform or inadequate flow. This arrangement canalso assist in ensuring the prevention of striations in the first andsecond faces 120 and 122 of the blank 14 from electrochemical machining.

The diverging nozzle 190 is preferred for reducing flow restrictiondownstream of the second throat 188.

It is also preferred that the converging nozzle 182 and the first throat184 be formed substantially symmetrically about a centerline axis 252disposed substantially normal to the first edge 124 and colinear withthe camber line 249. This is preferred to partly ensure that an equalvolume of electrolyte 28 is channeled over the first and second faces120 and 122. It is also preferred that the second throat 188 and thediverging nozzle 190 also be disposed substantially symmetrically abouta centerline axis 254 disposed normal to the second edge 126, andcolinear with the camber line 249, to additionally assist in ensuringequal volumes of flow of the electrolyte 28 over the first and secondfaces 120 and 122. However, for certain blade shapes the aboveorientations may be made unsymmetrical for obtaining equal volumes offlow of electrolyte 28 over the faces 120 and 122.

The outlet plenum 206 of the outlet block 198 is preferably convergingto the bushing 202 to transition in a relatively short distance from therelatively long outlet 192 to the circular return conduit 36.

Inasmuch as the seal pads 228 and 234 prevent the leakage of flow fromthe converging nozzle 182, the first throat 184, the second throat 188,and the diverging nozzle 190, obtaining a uniform radial flow profile ofthe electrolyte 28 is assisted.

The present invention additionally includes means for simultaneouslyelectrochemically machining the land 132 of the workpiece 12 into afinal platform 114. FIGS. 10, 11 and 15 illustrate a bottom work edge,or land, 256 of the work face 158 of the first electrode 18 which issubstantially colinear with an outer surface 257 of the seal pad 228. Asecond bottom work edge, or land, 258 of the work face 172 of the secondelectrode 20 is substantially colinear with an outer surface 259 of theseal pad 234. Both bottom edges 256, 258 are appropriately arcuate tomatch the curvature of the platform 114.

FIG. 18 illustrates electrochemical machining about the bottom edge 258with similar machining occurring also about the bottom edge 256. Thebottom edge 258 is shown in its initial position just prior toelectrochemical machining. The blisk 100 and the platform 114 are shownin a final machined position. Shown in dashed lines are the initialpositions of the blank 14 and the land 132 just prior to machining. Alsoshown in dashed line 260 is the final position of the bottom edge 258after machining.

FIG. 18 illustrates that a portion of the electrolyte 28 is channeledfrom the working space 186 radially inwardly toward the land 132 andthen axially outwardly substantially parallel thereto. The bottom edge258 includes a corner edge 262 which electrochemically machines acomplementary corner edge 264 into the blade 100 at the root 112thereof. The bottom edge 258 simultaneously machines the root 112 of theblade 100 and a portion of the platform 114 of the blisk 12.

It will be noted that the electrolyte 28 flows primarily in a transversedirection over the blank 14 from the first edge 124 to the second edge126 as illustrated in FIG. 17. Inasmuch as the bottom seals 224 and 226do not extend over the working portion 186 as illustrated in FIGS. 12and 14. The electrolyte 28 is allowed to flow radially out of theworking space 186 and then transversely over both bottom edges 256 and258 for machining the land 132 as above described. Accordingly, theelectrolyte 28 transitions from flowing in the transverse direction tothe radial direction and then transversely for machining the land 132.

In accordance with a preferred embodiment of the invention, transitionmeans are provided to ensure that such transition of flow occurs withoutabrupt changes which could result in a local reduction or starvation ofthe electrolyte 28. Experience has shown that the lack of an adequatesupply of the electrolyte 28 can cause undesirable sparking, or arcing,and local striations in the blank 14.

More specifically, such transition means are illustrated in theexemplary embodiment shown in FIGS. 10-12 and 15. In particular, thefirst bottom seal 224 is shown as being positioned on the inlet side, orupstream, of the blank 14. As electrolyte 28 flows over the seal pad 228of the first seal 224, it must transition from transverse flow to radialflow as it flows over a downstream end 266 of the pad 228 as shown inFIG. 15. The transition means include the pad 228 having an innersurface 268 which is arcuate and diverging with respect to thetransverse direction of electrolyte flow 28 as shown in FIGS. 10 and 11.This is accomplished in the embodiment shown by the pad 228 having athickness decreasing in the downstream direction. The support end 229,to which the pad 228 is attached, has a shape complementary to the pad228 and has a portion which is spaced from the pad downstream end 266 todefine a first gap 270. And, similarly, the recess 232 includes anarcuate portion 272, which is complementary to the inner surface 268 andis spaced therefrom to define a second gap 274.

The gaps 270 and 274 are in flow communication with the convergingnozzle 182 so that a portion of the electrolyte 28 is channeled throughthe gaps and over the bottom edges 256 and 258 as shown in FIG. 15.

Accordingly, the transition means, including the arcuate inner surface268 and gaps 270, 274, cause the electrolyte 28 to transition smoothlyfrom the transverse direction to the radial direction upstream of theblank 14. This ensures an adequate supply of the electrolyte 28 flowingover the bottom lands 256 and 258 and, in particular, over the upstreamends thereof, for reducing the likelihood of sparking and striations.

Furthermore, similar transition means are provided for the second bottomseal 226. This is particularly desirable where the flow of electrolyte28 will be reversed so that it flows transversely from the second edge126 to the first edge 124, i.e. opposite to the flow direction shown inFIG. 17, for example.

This second transition means includes a similar, arcuate, diverginginner surface 276 of the seal pad 234, and complementary shaped supportend 235 and arcuate portion 278 of recess 236. The transition means alsoincludes gaps 280 and 282 defined between an end 284 of the pad 234 anda portion of the support end 235 and the arcuate portion 278,respectively. The gaps 280, 282 are in flow communication with thediverging nozzle 190. Accordingly, when the flow of electrolyte 28 isreversed to that shown in FIG. 17, the means including the inner surface276 and gaps 280, 282 provide an analogous smooth transition fromtransverse to radial flow.

When the flow of electrolyte 28 is as shown in FIG. 17, it will be notedthat the inner surface 268 of the pad 228 diverges, whereas the innersurface 276 of the pad 234 converges (see FIGS. 10, 11 and 14). In thismode of operation, the inner surface 276, which is at the downstream endof the blank 14, assists in providing a smooth transition of electrolytefrom the working space 186 near the bottom edges 256 and 258 into thesecond throat 188.

Accordingly, a single blade 100 and a portion of the platform 114 can befinally machined in one operation from the workpiece 12, without needfor additional machining operations thereof. Of course, the blade tips110 are conventionally ground at assembly to fit precisely within aturbine shroud. However, this is also done for blisks machined byconventional methods as well.

The portion of the electrolyte 28 which flows over the top edges 256 and258 is collected in the drain 38 for return to the electrolyte supply32. When the electrodes 18, 20 are used for machining a blisk 98,adjacent blanks 14, as illustrated in dashed line in FIG. 12, must beprotected from this electrolyte flow for avoiding unwanted machining.Accordingly, the electrodes 18, 20 may be provided with suitable reliefsor back surfaces 286 and 288, respectively, as illustrated in FIG. 11,which provide space for accommodating adjacent blanks 14. The backsurfaces 286 and 288 are suitably coated with any conventionalnonconductive material, such as epoxy, for preventing unwanted machiningof adjacent blanks 14 by the back surfaces 286 and 288.

Although the electrodes 18, 20 may also be used for machining singleairfoil blanks 14 not integral with a blisk, when they are utilized formachining blanks 14 for a blisk 98, the seal pads 228 and 234 provide anadditional advantage by reducing the amount of electrolyte 28 leakageover the shoulders 116 and 118 which would otherwise occur from betweenthe working portions 146, 150 away from the working space 186.

To additionally reduce leakage of electrolyte 28, the outer surfaces 257and 259 of seal pads 228 and 234, respectively, are curved andcomplementary to the curvature of the shoulders 116 and 118 to minimizethe gaps therebetween. The curvature of the former elements in theembodiments illustrated in FIGS. 15 and 17, for example, is relativelysmall and is not perceptible in the Figures. However, for relativelysmall diameter workpieces 12, such curvature would be larger and clearlyperceptible.

The seal pads 228 and 234 also provide electrical insulation to preventthe unwanted machining of the shoulders 116 and 118, which wouldotherwise occur without their use.

Inasmuch as the throat widths W₁ and W₂ are relatively large at theinitiation of machining (FIGS. 14 and 17), most of the electrolyte 28will flow transversely over the blank 14 from the inlet 180 to theoutlet 190, and relatively little of the electrolyte 28 will flow aroundthe bottom edges 256 and 258. Accordingly, suitable means are providedto provide back pressure in the outlet plenum 206 to ensure that aportion of the electrolyte 28 is suitably channeled over the bottomedges 256 and 258 for machining the land 132. In one embodiment of theinvention, suitable back pressure may be obtained by utilizing a valve294, as illustrated in FIG. 1, which is disposed in serial flow in thereturn conduit 36. By suitably adjusting the valve 294, back pressurecan be provided in the outlet plenum 206.

In accordance with another embodiment of the invention, a new andimproved method of forming the blisk 98 from the workpiece 12 having theplurality of circumferentially spaced blanks 14 is disclosed. Initially,the second turntable 74 indexes one of the blanks 14 into alignment formachining. The third translation means 76 translates the workpiece 12 tothe electrode pair. FIG. 15 illustrates the first blank 14 in a positionjust prior to being inserted between the electrode pair. The controlmeans 50 coordinates movement of the first and second electrodes 18, 20and the workpiece 12 in the X, U, C and Z directions for positioning thefirst and second electrodes 18, 20 adjacent to the first and secondfaces 120, 122 of the first blank 14. The power means 30 is then usedfor supplying a positive voltage to the first blank 14 and a negativevoltage to the first and second electrodes 18, 20 through the cables 46and 48. The electrolyte channeling means 26 is effective for channelingthe electrolyte 28 between the first and second faces 120, 122 of theblank 14 and the work faces 158, 172 of the first and second electrodes18, 20 for electrochemically machining the first blank 14. The controlmeans 50 is then effective for translating the first and secondelectrodes 18, 20 toward the first and second faces 120, 122 of thefirst blank 14 in the U and X directions and generally normal thereto.Simultaneously, the control means 50 is effective for translating theworkpiece 12 toward the first and second electrodes 18, 20 in the Zdirection.

The machine 15 is effective for providing independent translation of theelectrodes 18 and 20 and the workpiece 12 in the X, U and Z directions.However, such movement is coordinated for maintaining proper relativepositions between the blank 14 and the electrodes 18 and 20.Furthermore, the electrodes 18 and 20 may additionally be rotatedtogether in the C direction on the first turntable 56, which providesfor a twisting action for coordinating movement of the electrodes 18, 20down over a twisted blank 14.

During electrochemical machining, the movement of the blank 14 and theelectrodes 18, 20 is coordinated in the X, U, Z and C directions formaintaining a substantially uniform space of about 8 mils, for example,between the work faces 158 and 172 and the blank 14 for obtainingsubstantially uniform electrochemical machining without undesirablesparking. The machine 15 having the five degrees of movement X, U, Z, Cand B in accordance with the invention results in a relatively simplemachine which moves both the electrode pair and the workpiece 12 foraccurately maintaining relative positions thereof for obtaining finalelectrochemical machining of a blade in a single operation on a blank14.

Upon completion of machining of the first blank 14, the control means 50reverses the movement of the electrodes 18, 20 and the workpiece 12,withdraws the first blank 14 from between the electrodes 18, 20 andindexes the workpiece 12 in the B direction for placing in position anadjacent, second blank 14. The second blank 14 is then electrochemicallymachined in a manner similar to the first blank 14. Additional blanks 14are then sequentially formed until a final blisk 98 is formed from theworkpiece 12.

A significant feature of one embodiment of the invention is channelingthe electrolyte 28 in substantially a circumferential direction from thefirst edge 124 toward the second edge 126 over the first and secondfaces 120, 122. The first and second edges 124, 126 correspond witheither the leading and trailing edges 106, 108 or the trailing andleading edges 108, 106, respectively. In accordance with a preferredembodiment of the invention, the electrolyte 28 is channeled from thefirst edge 124 towards the second edge 126 for forming a trailing edge108 and a leading edge 106, respectively. Tests show that better controlof dimensions of the leading edge 106 is obtained if electrolyte flow isfrom the trailing edge 108 toward the leading edge 106.

Leading edges 106 and trailing edges 108, having a radius of about 0.005inch, have been accurately machined using apparatus constructed inaccordance with the invention.

The improved method may also include accelerating the electrolyte 28through the converging nozzle 182, then channeling the electrolyte 28through the first throat 184, the throat having a minimum area relativeto the nozzle 182, then channeling the electrolyte 28 along both thefirst and second faces 120 and 122 of the blank 14, then channeling theelectrolyte 28 through the second throat 188 having a minimum area withrespect to the diverging nozzle 190, and then channeling the electrolyte28 through the diverging nozzle 190.

The method may also include translating the first and second electrodes18, 20 toward each other such that portions of the first and secondthroats 184 and 188 electrochemically machine away material from thefirst and second edges 124 and 126 of the blank 14 for generatingfinally machined leading and trailing edges 106 and 108 which do notrequire any additional machining operations for completion.

The method may also include channeling a portion of the electrolyte 28from the working space 186 over the bottom edges 256 and 258 and betweenthe base 130 of the blank 14 and the first and second electrodes 18, 20for electrochemically machining the land 132 of the workpiece 12 intothe platform 114 of the blisk 98.

While there have been described herein what are considered to bepreferred embodiments of the invention, other modifications will occurto those skilled in the art from the teachings herein.

It is therefore desired to secure in the appended claims all suchmodifications as fall within the true spirit and scope of the invention.For example, although the sealing means disclosed herein are fixedlyconnected to one electrode and overlap the other electrode, they may beoppositely supported. Furthermore, inasmuch as substantiallycomplementary electrodes 18 and 20 are utilized, features on oneelectrode may be interchanged with features on the other electrode, forexample, the particular shape of the work faces 158 and 172. Yetfurther, shapes other than airfoil shapes may be machined in accordancewith the invention.

Furthermore, the flow of electrolyte 28 can also be either fromtrailing-to-leading edge or vice versa, or alternating therebetween;and, accordingly, the functional flow relationship of the inlet block194 and the outlet block 198 may be interchanged with respect to thefirst and second electrodes 18, 20.

Yet further, the invention may be used to machine blades of axiallyadjacent tandem blisks, i.e. two blisks integrally formed. However, insuch an arrangement the space between the blisks may be relatively smalland, therefore, may not allow the electrode pair 18, 20 to fit therein.Accordingly, another embodiment of the invention may omit the outletblock 198, seal pad 234 and most of the diverging faces 162, 176 to fitwithin the inter-blisk space. Instead of such elements a simpleelectrically insulating block (G-10 material) may be fixedly attached toone of the electrodes and overlap for reciprocal movement the otherelectrode to form a predetermined radial gap therewith. The block causesthe electrolyte to flow through the gap which becomes the dischargeoutlet of the second throat 188. The gap provides controlled backpressure instead of using the valve 294, and the discharged electrolyteis collected in drain 38 instead of return conduit 36. This embodimentallows for a shorter electrode pair to fit between tandem blisks and theblock also prevents unwanted machining of the second blisk because it isan electrical insulator.

Having thus described preferred embodiments of the invention, what isclaimed as novel and desired to be secured by Letters Patent of theUnited States is:
 1. A method of forming a blisk from a workpiece havinga plurality of circumferentially spaced workpiece blanks, each havingoppositely facing first and second side faces defined by a radiallyinner base, a radially outer top, a first edge, and a second edge, saidmethod comprising:positioning first and second electrodes adjacent tosaid first and second faces, respectively, of a first one of saidblanks; supplying a positive voltage to said first blank and a negativevoltage to said first and second electrodes; channeling an electrolytebetween said first blank and said first and second electrodes forelectrochemically machining said first blank; moving said first andsecond electrodes toward said first and second faces of said firstblank; and moving said first blank toward said first and secondelectrodes during said electrochemical machining of said first blank. 2.A method according to claim 1 wherein said first and second electrodesand said workpiece are translated independently from each other duringsaid moving steps.
 3. A method according to claim 1 wherein said firstand second electrodes translate toward said first blank and rotate withrespect thereto, and said first blank translates toward said first andsecond electrodes.
 4. A method according to claim 3 wherein said firstand second electrodes and said workpiece are moved independently fromeach other during said moving steps and are coordinated so that saidfirst blank is electrochemically machined into a first blade.
 5. Amethod according to claim 4 further comprising indexing said workpieceby rotation for aligning a second blank with said first and secondelectrodes and sequentially forming a second blade therefrom in asimilar manner.
 6. A method according to claim 4 wherein saidelectrolyte is channeled substantially circumferentially over said firstand second faces.
 7. A method according to claim 6 wherein saidelectrolyte is channeled from said first edge to said second edge ofsaid first blank for forming a blade having a trailing edgecorresponding to said first edge and a leading edge corresponding tosaid second edge.
 8. A method according to claim 6 wherein a portion ofsaid electrolyte is channeled between said face of said first blank andedges of said first and second electrodes for electrochemicallymachining a platform at said base of said workpiece.
 9. A methodaccording to claim 6 wherein said electrolyte is accelerated through aconverging nozzle formed between said first and second electrodes, thenchanneled through a first throat, then channeled along both said firstand second faces of said first blank, then channeled through a secondthroat, and then channeled through a diverging nozzle.
 10. A methodaccording to claim 9 wherein said first and second throats are definedby portions of said first and second electrodes, and said first andsecond electrodes are moved toward each other such that said portionselectrochemically machine away material from said first and second edgesof said blank.
 11. An apparatus for electrochemically forming a bliskfrom a workpiece having a plurality of circumferentially spacedworkpiece blanks, each having oppositely facing first and second facesdefined by a radially inner base, a radially outer top, a first edge,and a second edge, said apparatus comprising:a housing; a pair ofelectrodes including a first electrode and a second electrode; means formounting said electrode pair to said housing; means for mounting saidworkpiece to said housing; means for channeling electrolyte to saidelectrode pair; means for powering said electrode pair with a negativevoltage and said workpiece with a positive voltage; said electrode pairmounting means comprising: a first turntable attached to said housingand rotatable about a first axis; a first translation means attached tosaid first turntable for mounting said first electrode; a secondtranslation means attached to said first turntable for mounting saidsecond electrode; and said electrode mounting means being effective fortranslating said first and second electrodes toward each other and forrotating both said first and second electrode about said first axis;said workpiece mounting means comprising: a third translation meansattached to said housing; a second turntable attached to said thirdtranslation means and rotatable about a second axis; and said workpiecemounting means being effective for translating said workpiece towardsaid first and second electrodes and rotating said workpiece about saidsecond axis; and means for controlling movement of said electrode pairmounting means and said workpiece mounting means.
 12. An apparatusaccording to claim 11 wherein said control means is effective forrotating said second turntable to index a first blank into a machiningorientation and translating said workpiece to said electrode pair, andfor translating and rotating said electrode pair to a machining positionover said first blank.
 13. An apparatus according to claim 12 whereinsaid control means is effective for independently controlling said firstand second turntables and said first, second and third translationmeans.
 14. An apparatus according to claim 11 wherein said first andsecond axes are coplanar and substantially perpendicular to each other.15. An apparatus according to claim 11 wherein said electrode paircomprises:an electrically conductive first electrode having a supportportion and a working portion for electrochemically machining said firstface of said blank, said working portion having an inlet end and anoutlet end; an electrically conductive second electrode having a supportportion and a working portion for electrochemically machining saidsecond face of said blank, said working portion having an inlet end andan outlet end; said first and second electrodes being positionable aboutsaid blank for defining an inlet and an outlet between said inlet andoutlet ends, respectively, of said working portions of said first andsecond electrodes; means for channeling electrolyte from said inlet tosaid outlet, portions of said channeling means being fixedly connectedto at least one of said first and second electrodes; and means forsealing said working portions of both said first and second electrodesto substantially prevent leakage of electrolyte from said inlet andoutlet, portions of said sealing means being fixedly connected to atleast one of said first and second electrodes.
 16. An apparatusaccording to claim 15 wherein:said channeling means comprises anonconductive inlet block fixedly connected to said second electrode,said inlet block having an inlet plenum alignable with said inletdefined between said first and second electrodes; and a nonconductiveoutlet block fixedly connected to said first electrode, said outletblock having an outlet plenum alignable with said outlet defined betweensaid first and second electrodes; and said sealing means comprises aninlet seal defined by a sealing portion of said inlet block slidinglyengageable with said inlet end of said first electrode; and an outletseal defined by a sealing portion of said outlet block slidinglyengageable with said outlet end of said second electrode.
 17. Anapparatus according to claim 16 wherein said sealing means furthercomprises a top seal defined by a nonconductive seal block fixedlyconnected to one of said first and second electrodes, and acomplementary recess disposed in the other of said first and secondelectrodes, said top seal being positionable over said top of saidblank.
 18. An apparatus according to claim 17 further including a firstbottom seal for preventing electrolyte from leaking radially outwardlyfrom said converging nozzle and said first throat, and a second bottomseal for preventing electrolyte from leaking radially outwardly fromsaid second throat and said diverging nozzle.
 19. An apparatus accordingto claim 18 wherein said first and second bottom seals each includes aseal pad fixedly attached to one of the electrode pair, and acomplementary recess in the other of the electrode pair for receivingsaid pad in sealing engagement therewith.
 20. An apparatus according toclaim 19 wherein said first bottom seal is disposed in an upstreamposition relative to said second bottom seal, and further comprisingtransition means including an arcuate, diverging inner surface of saidseal pad of said first bottom seal for transitioning electrolyte flowfrom a transverse direction to a radial direction for flowing over saidbottom work edges.
 21. An apparatus according to claim 20 wherein saidtransition means further includes gaps formed between a portion of saidseal pad of said first bottom seal and said electrode pair forchanneling electrolyte therethrough to flow over said bottom work edges.22. An apparatus according to claim 15 wherein:said working portion ofsaid first electrode includes in sequential placement from said inletend to said outlet end thereof a converging face, a first throat face, awork face, a second throat face, and a diverging face; said workingportion of said second electrode includes in sequential placement fromsaid inlet end to said outlet end thereof a converging face, a firstthroat face, a work face, a second throat face, and a diverging face;and said first and second working portions are positionable to face eachother and define a converging nozzle between said converging faces, afirst throat between said first throat faces, a working space betweensaid work faces in which said blank is positionable, a second throatbetween said second throat faces, and a diverging nozzle between saiddiverging faces.
 23. An apparatus for forming a blisk from a workpiecehaving a plurality of circumferentially spaced workpiece blanks, eachhaving oppositely facing first and second side faces defined by aradially inner base, a radially outer top, a first edge, and a secondedge, said apparatus comprising:means for positioning first and secondelectrodes adjacent to said first and second faces, respectively, of afirst one of said blanks; means for supplying a positive voltage to saidfirst blank and a negative voltage to said first and second electrodes;means for channeling an electrolyte between said first blank and saidfirst and second electrodes for electrochemically machining said firstblank; means for moving said first and second electrodes toward saidfirst and second faces of said first blank; and means for moving saidfirst blank toward said first and second electrodes during saidelectrochemical machining of said first blank.